Centrifugal drier



June 9, 1925.

T. O. WESTHAFER ET AL CENTRIFUGAL DRIER Filed April '7. 1920 Patented June -9,' 1925.

UNITED SV'TATES. P ArE;uroFF1c TERRENCE 0. WESTHAFER, or PUEBLO, COLORADO, AND F MERLE MILLER, OF

CHICAGO,

ILLINOIS.

CENTRIFUGAL DRIER.

Application filed April 7,

T 0 all whom it may concern:

Be it kn'own.that we, TnRRnNCu O. VEST- nArnR, a citizen of the United States, residing in the city of Pueblo, county 0t Pueblo, and State of Colorado, and Fun!) MERLE MILLER, a citizen of the United States, residing in the city of Qhicago, county of Cook, and State of Illinois, have invented certain new and useful Improve;

ments in Centrifugal Driers; and we do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same. i

This invention relates tocentrifugal driers and more particularly to continuous centrifugal machines for drying granular material such as coal, ammonium nitrate, ammonium sulfate, sugar and the like.

Most of the centrifugal coal driers at present in use are of a semi-continuous vertical type .in which the coal is collected in pockets, compartments, or on segmental areas while drying and intermittently discharged from said parts. By such action the drier is subjected to variable and intermittently, changing forces. The upkeep of these machines is also very high due to the fact that the entering material impinges heavily on the perforated lining and due to the fact that the various forces are unbalanced,- thus placing a heavy thrust on the'bearings. Further, a large amount of power is consumed 1 in bringing the incoming material up to the centrifugal drying speed and a still larger amount of power is lost in dischargingmaterials from the drum while rotating at a high speed. Usually these feeding and discharging operations act to undesirably break up or pulverize the coal, the initial pulverizing tending toprevent effective drying.

The primary object of the present invention is to provide a centrifugal machine by which material may be effectively dried with a minimum expenditure of power and with a minimum breaking up of the material being treated.

Another object of the invention is to pro 'vide a centrifugal machine in which material maybe moved axially of a rotary drum without placing the thrust on the bearings of the drum.

A" further object of the invention is to provide a continuous centrifugal machine 1920. Serial No. 371,829.

by which material may be placed inand removed from the drum without requiring an excessive expenditure ofenergy and with minimum breakage of the material being treated. v M W'ith these and other objects in view, the invention consists in the improved centrifugal drying machine hereinafter described and specifically defined in the claims.

The various features of the invention are illustrated in the accompanying drawings. in which, I i I ligure 1 a top plan view, party in sect on, of a centrifugal drying machine embodying the preferred form of the inven t1on-;

Fig. 2 isa vertical sectional view of the centrifugalmachine shown in F ig. 1; and

Fig. 3 is a detail sectional View of the ring tor continuously discharging material from. the centrifugal drum.v J

The centrifugal machine-illustrated in the drawings is of the continuous type in which material is continuously fed in at the end of the drum, the materialth'en moving axially of.the drum while drying and continuohslydischarging through a central peripheral outlet. The centrifugal drum 10 comprises twp frustro-conicalsections 12 and 14 which i I the trunnion 18 by which a rotary motion may be imparted to the drum. W'fththe exception of the pulley 32, the centrifugal drum 10 is symmetrically arranged with reference to its longitudinal and transverse axes. By maintaining the drum in proper running balance, its construction is well adapted for high speed rotation without undue centrifugal strain being placed on the rotating parts or an excessiveconsumption of power. The material to be dried is fed into the drum through the trunnions 18 and 20 and passes axially of the sections 12 and 14 across perforated screens 34 and 36 which are secured to the frame-work of the sections 12 and 14. By the time the material is advanced across the screens 34 and 36, it will have become dried and is then discharged through the discharge ring 16..

' blades.

screw while the screw charged from the drum The axial movement of the material through the drum while drying is controlled primarily, by screw conveyors rotatably mounted within the drum, and secondly, by thetangle of inclination of the walls of the frustro-conical sections with the longitudinal axis of the drum. The screw conveyors 38 and 40 are mounted within the drum with the outer edge of the conveyor blades in close proximity to the inner surface of the screens 34 and 36; the screw 38 being a right-hand 40 is a left-hand screw. The-pitch of the screws 38 and/l0 are substantially the same but opposed and are arranged to advance the material axially of the drum from both ends toward the center at a substantially uniform rate n order to maintain a balanced relation in the drum while the material is being dried. The conveyors 38 and 40 are keyed to. ashaft 42 which is journalled in bearings 44 and 46 mounted on stands 48 and 50 secured to the base 30. A pulley 51 is mounted on the shaft 42 adjacent the bearing 44 by which the conveyors may be rotated independently of the rotation of the centrifugal drum.

The relative speed of rotation of the drum 10 and the conveyors 38 and 40 also has a distinct control upon the axial advance of material through the drum and may be varied when drying different kinds of materials. Experiment has proven that in drying'coal the best angle of inclination of the walls of the sections 12 and 14 with reference to the longitudinal axis of the drum is approximately 25. With this inclination, the conveyor screws 38 and 40 act to retard the ,advance of coal across the screens 34 and 36 rather than-to advance the material, and in this way the material will advance without an undue wear upon the screens or conveyor By means of the three factors, that is, the pitch of the screws of the conveyors 38 and 40, the inclination of the .walls of the conical sections 12 and 14 with reference to the longitudinal axis of the drum, and the relative speeds of rotation of'the conveyors and drum, any kind of material may be properly advancid through the centrifugal drum while maintaining a balanced condition of the machine andv without placing an undue wear upon the conveyor or drum. In most cases, how- 'ever, a variation of the relative-speeds of the drum and conveyors will permit the proper drying of different kindsof material whilemaintaimnga fixed angle of inclination of the frustro-conical sections with reference to the longitudinal axis and a fixed pitch of the screw conveyors. I

' The manner in which wet-material is fed into the drum and dry material is disform a very important feature of the present invention. By

means of the construction illustrated in the screens sections 12 and 14. in advancing the material through the spouts 52 and 54, the conveyors 38 and 40 bring it up to substantially the speed of rotation of the smaller ends of the drum 10 and deliver the material to the smaller ends of the drum in a peripheral stream. As the material leaves the ends of the spouts 52 and 54, it is placed upon the ends of the drum demand of energy from the centrifugal drum. The hoppers 56 and- 58iare preferably connected with a common supply chute by which a'uniform supply of material may be maintained in the hoppers. 1

The dried material is dischargedfrom the drum through a series of curved outlets 60 arranged around the peripheryfof the discharge ring 16. The outlets 60 are formed by a seritsof curved blades 62, the leading edge of each blade being arrangedto overlie radially the-trailing end of the preceding blade. With this construction, the material 10 with substantially no being discharged cannot pass radially out through the opening 60 but must impinge against a blade 62 and this impingement I and its movement across the curved surface of the blade 62, it imparts the excess port1on of its kinetic energy to the ring 16 which energy thus is absorbedin. the drum By this means the material will not leavethc drum at an excessively high rate of speed so that it will not--be unduly pulverized when it is discharged into an outlet passage 64 formed in a casing 66 immediately opposite the discharge ring 16. .To assist in removing material from the discharge passage 64, blades 68 are stcured to tlie discharge ring and extend radially only partially the depth of the passage 64. The

blades 68 carry the material around the p'as-. sage and discharge it through a bottom outlet 70 formed in the base 30. Since .the

blades 68 do not extend to the bottom of the passage 64, a'bed of material will always be maintained in the passage 64 andthus the discharging material will not act to wear out the casing in the passage.

The moisture and dirt removed from the material being dried passes through the 34 and 36 and are caught in collecting sections 72 and 7 4(jformed in the casmg 66 at the opposite sides of the passage 64. The material collected in the sections 72 and 74, drains to wells 76 and may be removed through outlets 78.

As shown in. Fig. l, the pulley 32- is connected by means of a belt 80 with a pulley 82 mounted on a power-driven shaft 86. The pulley 51 is connected by means of a belt 88 with a pulley 90 on the power shaft 86. The relative size of the pulleys 51, 90, 82 and 32 may be varied in developing any desired relative rates of speed of the drum and screw conveyors.

The preferred form of the invention having been thus described, what is claimed as new is:

1. In a centrifugal drier, the combination of a perforated rotary drum, a peripheral discharge intermediate the ends of the drum, means for feeding material into both ends of the drum, means for rotating the drum at. a sufliciently high speed to'hold said material against the drum by centrifugal force, and means to advance the material from the ends of the drum to said discharge.

2. In a centrifugal drier, the combination of a perforated rotary drum, a peripheral discharge intermediate the ends of said drum, means for feeding material into both ends of said drum, means for rotating the drum at a sufficiently high speed to hold said material against said drum by centrifugal force, and conveyors operated i11- dependen'tly of said drum to advance the material from the ends of the drum to said discharge.

3. In a centrifugal drier, the combination of a perforated rotary drum, a peripheral discharge intermediate the ends of said drum, means for feeding material into both ends of said drum, means to rotate said drum and 'sharp pitched right andleft hand screw conveyors mounted within said drum between its ends and said discharge, and means for rotating said conveyor.

4. In a centrifugal drier, the combination of a perforated rotary drum, comprising opposed frustro cones having their largest diameters at the mid portion of said drum, peripheral discharge openings in said mid portion, means for feeding material into opposite ends of said drum, a conveyor mounted in said drum arranged to control the advance of material toward said discharge, and means for rotating said drum and conveyor. I

5. In a centrifugal drier, the combination of a perforated rotary drum, comprising opposed .frustro-cones having their largest diameters at the mid portion of said drum, peripheral discharge openings in said mid portion, means for feeding material into opposite ends of said drum, a conveyor mounted in said drum having opposed screw-conveying blades mounted in said frustro cones, means for rotating said drum,

and independent means for rotating said conveyor.

6. In a centrifugal drier, the combination of a rotary drum, means for rotating said drum at a high speed, a. feed-spout extending into said drum with its discharge end mounted in close proximity to the inner wall of said drum, and means to deliver material through the discharge end of said spout around its periphery at a speed approximately the same as that of the adjaeter of ,the inner wall of the drum at the position of the end of the spout, a screw conveyor mounted in said spout and means for rotating said conveyor.

S. In a centrifugal drier, the combination of a rotary frustro-conical drum, a feed-spout arranged to project into the smaller end of said drum with its discharge end in close proximity to the inner Wall of the drum, a discharge adjacent the larger end. of said frustro cone, a helical conveyer in said spout with its blades arranged to move in close proximity to the inner surface of the spent, a conical screw conveyor mounted adjacent the inner wall of said frustro cone,- and means for rotating said drum and conveyors.

9. In a centrifugal drier, the combination of a perforated rotary drum, comprising op-,

posed symmetrically arranged frustro cones having their largest diameters at' the mid portion of said drum, peripheral discharge openings in said mid portion, means for feeding material into opposite ends of said drum at a uniform rate, a conveyor mounted in said drum arranged to advance material being dried uniformly toward said dis charge, and means for rotating said drum and conveyor.

10. In a centrifugal drier, the combination of a perforated drum mounted to rotate about a horizontal axis with discharge outlets symmetrically arranged at the center of the longitudinal peripheral surface of said drum, screw conveyors mounted in the, drum with their peripheral surface in close proximity to the inner surface of said drum, the pitch of said conveyors being opposed and equal, means for rotating said drum, and means for rotating said conveyors at a substantially uniform speed.

11. In a centrifugal drier, the combination of a perforated drummounted to rotate peripherally on a horizontal axis, and a conveyor mounted in said drum arranged to advance material axiallyof said drum while the material is held against the drum by centrifugal force, said conveyor being arranged to develop opposing forces in the axial movement of the material through the drum to prevent thrust on the bearings of said drum.

12. In a centrifugal drier, the combination of a perforated drum mounted to rotate on a horizontal axis, means to advance material axially of said drum from both ends toward the center thereof with substantially equal thrusts, and means to deliver material to the opposite ends of said drum with opposed and substantially equal thrusts.

13. In a centrifugal drier, the combination of a perforated drum mountedto rotate on a horizontal axis, means to advance material axially of said drum from both ends toward the center thereof with substantially equal thrusts, and means to deliver material to the opposite ends of said drum at a speed approximately equal to the normal peripheral speed of the endsof said drum.

14. In a centrifugal drier, tion of a rotary drum, means rial to said drum, means the combinato feed mateto advance materia rial to said drum, means to axially of said drum, and a series of spaced 3 discharge blades mounted in the periphery of said drum, said blades having a curved shape arranged to absorb kinetic energy of the material being discharged.

15. In a centrifugal drier, the combination of a rotary drum, means to feed mateadvance mate rial axially of said drum, and a series of spaced discharge blades mounted in the periphery of said drum, said blades being shaped so that the leading edge of one blade will'radially overlap the trailing edge of the adjacent blade.

.16. in a centrifugal drier, the combination of a rotary drum, means to feed material to said drum, means to advance niate,

rial axially of said drum, a series of discharge openings formed in the periphery of said drum, a collecting passage surrounding said drum opposite said openings, an outlet for said passage, and a plurality of scrapers mounted on said drum and extending radially only partially the depth of said passage.

In witness whereof we affix our signatures.

FRED MERLE, MILLER. TERRENGE o.; WESTHAFER. 

